With advances in computer networking combined with the development of powerful home computers and modern operating systems, the ability to provide streaming media has become more viable and in turn the demand for such streaming media has significantly increased. As the demand for streaming media increases, the ability to perform near real time delivery of a high quality media asset to a destination media receiver with a limited amount of available access bandwidth has become increasingly important. Known encoding methods (e.g., moving pictures experts group (MPEG) standards) allow media streams to be encoded as either constant bit rate (CBR) or variable bit rate (VBR). The bit rate associated with compressed data normally varies over time since the image complexity and changes between frames fluctuate over time. Encoders configured to generate VBR media streams typically keep video quality constant over time and vary the bit rate while encoders that generate CBR media streams keep bit rate constant and vary the video quality over time. The peak rate of many known VBR encoded media streams is typically 2-3 times higher than that of the average rate.
In known streaming media systems (e.g., internet protocol television (IPTV)) the bandwidth accounting used for admission control must use the peak rate associated with VBR streams in order to ensure that internet protocol (IP) packets associated with the video class do not experience congestion or drop during periods of peak bandwidth usage. When the admission control is performed based on VBR peak rate, the actual bandwidth used with video, for example, is underutilized most of the time. As a result, most known streaming media systems (e.g., IPTV) that utilize encoded VBR media streams (e.g., MPEG) employ rate clamping to reduce the peak rate of each VBR stream. Rate clamping is performed with a trans-rating function (e.g., an MPEG trans-rating function) that is computationally expensive and causes video quality degradation during periods where image complexity or motion is high. In addition, the conversion results in extra data (e.g., padding bits) being added to the media stream when the bandwidth of the original VBR stream is lower than the target CBR rate. Consequently, the average bandwidth of a CBR stream, derived from a VBR stream by performing rate clamping, is typically higher than the average rate of the VBR stream it was derived from. The resulting CBR stream is therefore less efficient (e.g., requires more bits) than the original VBR stream and thus, requires more bandwidth on average to transmit than does the original VBR stream.